As will be understood from the following description, the present invention was developed for improving bivouac (hereinafter bivy) sacks. This invention may also find utility in other environments, such as tents and weather resistant sleeping bag shells.
Conventional bivy sacks are made from breathable materials that allow occupant produced moisture to escape while protecting the occupant from the environment, e.g., rain, snow, etc. However, an occupant tends to produce more moisture than what can escape through these breathable materials. Therefore, excess moisture accumulates within the bivy sack. On a foul weather day the occupant stores equipment and extra clothes within the bivy sack to keep them dry from the foul weather. This purpose is defeated when the accumulated moisture soaks the equipment and clothes.
A partial solution for improving the comfort in personal shelters is shown in the VL Wing tent produced by Mountain Hardwear. The VL Wing tent includes a square cross-sectioned, vertically hanging vent structure for promoting air flow within the tent. However, this vent structure is ineffective at decreasing moisture within the tent, because the tent fails to include coordinated vertical ventilation. The tent duct is oriented along an inverted V shaped path, having inlets to the outside air at the lowermost ends of the duct, and an outlet to the tent interior at the highest center point, i.e. at the apex of the tent. Because the warm, moist air inside the tent is less dense than the cold outside air, there is no mechanism to cause air to flow through the duct and outside. This design thus provides no effective mechanism for carrying moist air outside of the tent.
The present invention provides a new and improved personal shelter with improved moisture evacuation and ventilation.